Search results

Search Forums New Posts
  1. BobK

    Can a Chopper Realistically Be Built

    Pull up the brochure that the OP posted. Full wave rectified, and they sjow a smoothing capacitor as well. Bob
  2. BobK

    Can a Chopper Realistically Be Built

    The "chopper" or the more complicated "inverter" are what we call a buck converter and a flyback converter in the electronics world. These are the only reasonable ways to reduce 90V to 30V at that kind of current. As kelleys_eye says, the current can be handled by parallelled MOSFETS. I would...
  3. BobK

    Wiring LEDs to Corresponding Switches?

    Are you saying that you have 30 12V LEDs and 30 switches with 5V LEDs inside? A link to the products would be helpful. Bob
  4. BobK

    Can a Chopper Realistically Be Built

    Sounds like a description of a buck converter to me. And the frequency is only 20KHz. Yes, 300 Amps is a lot, but I would think I could build one for less than $2000. There is another reason why it might be so expensive. Lincoln is the only company that offers this, so the likely have an...
  5. BobK

    Can a Chopper Realistically Be Built

    Well, if the chopper requires as many parts as a car, I will cocede your point. Bob
  6. BobK

    Can a Chopper Realistically Be Built

    Well, $2000 does not sound like a cheap mass-produced item. I know nothing about welding, so, what does a "chopper" do? Bob
  7. BobK

    Constant device failure

    This would certainly show up if the voltages of both phases were recorded. Bob
  8. BobK

    The shape of schematic components

    There is no standard way to place the pins on ICs in a schematic. Some are layed out like the physical device. Others are layed out more by function. Some devices come is diferent packages, eg. through-hole and SMT with different pin layouts. You can always make your own symbol the way you...
  9. BobK

    Constant device failure

    This is a question, not a suggestion. Can the bad ground connection be at the transformer instead of at the panel? I would think that would cause the same problems. Don't know enough about home service, but I seem to have only 2 wires coming from the utility po.e for my 2 phases (U.S.) That...
  10. BobK

    Bitwise AND assignment

    0x80 is the high bit only set in a byte. It is shifted right by some amount i, getting a selected single bit set in the byte. Then that is complemented, getting all other bits set. Finally, it is anded with the data. This retains all bits in the data except the one selected bit. This is...
  11. BobK

    Too much current with 5v, how to handle or resize?!

    You can split the power any way you want, and each cable is required only to carry the current it might be supplying. I presume you will have some arrangement of multiple stripes, each several meters long. I would use one cable to each end of each stripe. With 15 meters, you are talking...
  12. BobK

    Measuring the current used in a power supply?

    True, but if you can tolerate 3.29 V it can be done. You need a low value (say 0.01Ω) resistor and a comparator to do this. It would drop 8mV at 800mA. Bob
  13. BobK

    fast optical switch circuit to turn on 3V 1A supply - please help

    Actually, they use phototransistors. If you look at the specs, the photodiodes are way faster, measured in 10s of nanoseconds, whereas phototransistors are typically several microseconds. The trick would be getting the amplification needed without increasing the delay to over 1 uS. Bob
  14. BobK

    fast optical switch circuit to turn on 3V 1A supply - please help

    I don’t think you will find an optocoupler ir SSR with 1 microsecond response time. I think a crcuit based on a photodiode will be required. Bob
  15. BobK

    Help with a "simple" 555 circuit

    In that case, it sounds like the action is taken on button up. Perhaps reversing the the cap and resistor would work. That would simulate holding the button down before turning on power then releasing it. Have you tried that as well? Bob
  16. BobK

    Help with a "simple" 555 circuit

    What happens if you press and hold the button? If this puts it in the right mode, a resistor and capacitor might do it. You would have a capacitor from V+ to the button input and a resistor from there to ground to simulate that. Bob
  17. BobK

    Mini project, need some advice.

    I really doubt that you need 24 pins. The project you are looking at uses and external ADC to read an analog temperature sensor. the DHT22 does not use an analog interface, and, even if it did, the PIC has the ADC built in, so that is 8 pins you do not need. The LCD can be run with 6 pins...
  18. BobK

    Mini project, need some advice.

    Basically, any but the very smallest PICs could do this. To choose one, list all the inputs and outputs that you need. Add a few extras just in case, and start looking at PICs with that many I/O pins or more. The PIC16F84A is a very old obsolete PIC. You can get many more features with newer...
  19. BobK

    Audio Amplifier Design

    Do you have the + and - supplies that circuit requires? Bob
  20. BobK

    Super bright led light

    Text them. Bob
Top